Reported measurement uncertainty for TEOM FDMS analysers has been increased from 8.7 to 11.8% for PM10 and from 16.4 to 18.2% for PM2.5 with effect from 1/1/2019. A change in the manufacturing of the tapered element filter has led to the manufacturer recommending the relaxing of tolerances for testing the k0 calibration factor. The uncertainty limit for the equivalence standard method is 25%. The equivalence status of the TEOM FDMS analyser is unaffected by this change.
Introduction to monitoring data
There are three types of data stored in this section and these are outlined below.
1. Monitoring data
There are over 1500 sites across the UK that monitor air quality. They are organised into networks that gather a particular kind of information, using a particular method. There are two major types - automatic and non-automatic networks. The Monitoring Networks section provides further network information. Download data from the networks using the Data Selector Tool or download raw automatic data using the preformatted files link.
2. Descriptive statistics
For each monitoring site you can select a range of statistics which are relevant to the particular monitoring method. Basic statistics are annual mean, maximum and minimum values, with daily means, monthly means and a range of percentile values available where these are meaningful.
3. Exceedance statistics
Exceedance statistics provide information about concentrations above a specific threshold value. The exact concentration and the metric used varies by pollutant and purpose. A selection of commonly used examples are the UK Air Quality Objectives, EU Limit and Target Values, Critical Loads, the health-effects based system of four bands and a 1-10 index and the Indicators of Sustainable development - the average number of days per site on which pollution levels were above National Air Quality Standards.
You can select any of these exceedance statistics for a range of time periods, pollutants and locations.
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